BLE Scanning at Start in Swift

Question

I have scanning for a single UUID working in my Swift app when attached to an IBAction: UIButton . However, I'm now trying to get it to start scanning right when the app starts (background scanning should also be working as I have it set to a single UUID ).

I've tried what I think is logical:

self.centralManager?.scanForPeripheralsWithServices(arrayOfServices, options: nil)

in viewDidLoad with arrayOfServices being the UUID of course. But this doesn't seem to work.

How do I get my app to look for peripherals upon start up without being prompted with a button press?

Answer 1

You will need to initialize the CentralManager and wait for the centralManagerDidUpdateState call via the CBCentralManagerDelegate. Once you verify that the State is PoweredOn, you can start scanning.

func centralManagerDidUpdateState(central: CBCentralManager) {

    switch central.state
    {
    case CBCentralManagerState.PoweredOff:
        print("Powered Off")
    case CBCentralManagerState.PoweredOn:
        print("Powered On")
        //Start Scanning Here
         self.centralManager?.scanForPeripheralsWithServices(arrayOfServices, options: nil)
    case CBCentralManagerState.Unsupported,
         CBCentralManagerState.Resetting,
         CBCentralManagerState.Unauthorized,
         CBCentralManagerState.Unknown:
        print("Unexpected CBCentralManager State")
        fallthrough
    default:
        break;
    }
}

Answer 2

Swift 3

func centralManagerDidUpdateState(_ central: CBCentralManager){

    switch central.state{

    case .poweredOn:
        print("Power On")
        central.scanForPeripherals(withServices: nil, options: nil)     
        break

    case .poweredOff:
        print("Power Off")

        break

    case .unsupported:
        print("Power Unsupported")
        break

    case .resetting:
        print("Power Resetting")
        break

    case .unauthorized:
        print("Power Unauthorized")
        break

    case .unknown:
        print("Power Unknown")
        break
    }
}